"Sex-positive" proponents do not teach about sex to kids (children, adolescents, teens, young adults, etc.) to inform them of the mechanics or the keep them from getting pregnant. They seek to teach them to have sex because sex is fun. Sex is appropriate at any age and sex acts of all stripes are acceptable.
Some sex-positive proponents are hesitant to say anything against adult-minor or incest sexual experiences because that would be making a value judgement. About the only thing they are against is rape (although rape fantasies are okay).
You obviously weren't around in the 60's... That dam burst a *long* time ago, and it hardly needed "the homosexual agenda" to "open the floodgates".